Extensible support



FIG. 1 is a perspective view of the extensible support, showing my new design;

FIG. 2 is a left side elevation of the extensible support;

FIG. 3 is a rear elevation thereof;

FIG. 4 is a top elevation thereof; and,

FIG. 5 is a bottom elevation of the extensible support illustrated in FIGS. 1-4. 

The ornamental design for an extensible support, as shown and described. 